Currently children can consent to medical treatment without parents´ knowledge or consent: Case law results eg Gillick Competence Test for minors to get contraception allow them to decide what happens to their bodies; through it they may consent to a wide range of medical treatment, which is wrong.
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Contraception alters a natural bodily function for a voluntary act and is an issue aside; medicines, vaccines and other treatments prevent involuntary illness from a malfunction of the body or protect it from foreign elements (bacteria, viruses, irritants etc). Minors may not understand issues such as need, risk, being in trial phases etc: parents must be involved in all circumstances (this does not refer to rapid response situations when life-saving treatment is needed) and that should be law.